Portable swimmer propulsion unit

ABSTRACT

A portable swimmer propulsion unit including a vane type gas motor driving a shrouded screw. A positive expulsion, boot strap, hydrazine feed system supplies hydrazine to a hydrazine decomposition reactor. Gas from the reactor serves to drive the gas motor.

United States Patent 1191 Geres 1 Aug. 27, 1974 PORTABLE SWIMMER PROPULSION UNIT [75] Inventor: Robert J. Geres, China Lake, Calif.

[73] Assignee: The United States of America as represented by the Secretary of the Navy, Washington, DC.

22 Filed: 114111.24, 1972 21 App]. N6; 237,814

[52] US. Cl. ll5/6.1, 60/64 [51] Int. Cl B63b 21/56 [58] Field of Search 1l5/6.l, 6; 114/16 G;

[56] References Cited UNITED STATES PATENTS 8/1953 Mikulasek et aI. 123/1 A 7/1962 Egbert et al. 60/246 GAS OPERATED PUMP GAS EXHAUST (MUFFLER) A/INATER INTAKE A/FILTER RELIEF VALVE HAND THROTTLE (FUEL METERING VALVE) vvvvvvvvvvv 42mm FUEL TANKS (POSITIVE EXPULSION) 3,066,638 12/1962 Andresen ll5/6.l 3,091,520 5/1963 Newbum 60/257 3,293,851 12/1969 1111113611 6121 115/6.l 3,298,182 1/1967 Webb 60/257 3,477,223 11/1969 1611115611 2 .....,....60/37 Primary Examiner-Trygve M. Blix Assistant Examiner-D. C. Butler Attorney, Agent, or FirmR. S. Sciascia; Roy'MiIler; Robert F. Beers [57] ABSTRACT 1 Claim, 2 Drawing Figures GAS MOTOR IVANE TYPE) 1 DECOMPOSITION CHAMBER (SHELL 405 CATALYST) BACKGROUND OF THE INVENTION 1. Field of the Invention This invention pertains to portable underwater swimmer propulsion devices.

2. Description of the Prior Art Presently, two primary types of propulsion are employed in underwater swimmer propulsion units:

One type is driven by compressed air. The greatest disadvantages to this type of propulsion system is that the energy density is extremely low. A compressed air system of equal external volume producing power equal to that of the present invention viz. /2 horsepower continuously at 1,000 foot depth with a positive displacement/motor will last for only about 30 seconds compared to around 20 minutes for the present invention. Other compressed air devices such as shown in US. Pat. No. 3,066,638 last considerably longer than 30 seconds but have an extremely low power output.

A compressed gas tank also presents a safety hazard due to the high pressures necessary inside a compressed gas tank.

The most commonly employed type of portable underwater propulsion is an electric motor driven by batteries. There are many disadvantages to a battery powered system as compared to the present invention:

Batteries can hold their charge only a comparatively short time in storage whereas hydrazine can be stored indefinitely (for at least years) without losing any energy.

At low temperatures a battery will lose power whereas temperature has no effect on a hydrazine reaction.

In order to throttle a battery, one must use either a rheostat with a resultant energy loss or intricate switching circuits which provide throttling only in steps. The present invention may be throttled with a simple fuel metering valve and with no resultant loss of energy.

To recharge a battery type system it must ordinarily be resurfaced and attached to a battery charger for up to four hours. whereas the present invention can be re fueled underwater by replacement of the fuel element or by attaching it to a surface hydrazine source either of which takes approximately 30 seconds to perform.

Batteries are not as efficient under continuous operation as hydrazine. It is well known that batteries operate more efficiently if they are shutdown intermittently.

Liquid hydrazine may be stored in any shape, whereas a container must be built to conform to the shape of a battery or a specially designed battery must be built to conform to the shape of a container. A battery powered unit must be sealed to prevent shorts, whereas water leakage into a hydrazine tank does not prevent its operation byt merely lowers the efficiency of it. A 50-50 mixture of hydrazine and water will still react.

SUMMARY OF THE INVENTION The invention is an underwater portable swimmer propulsion unit in which a vane type gas motor drives a propeller. Gas for the motor is derived from a hydrazine decomposition reactor connected to positive expulsion hydrazine fuel tanks. Exhaust from the motor serves to drive a gas operated pump which pumps water into the fuel tanks to displace the hydrazine into the decomposition chamber.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic of the invention; and FIG. 2 is an axial cross section of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 2 shows a piston type hydrazine expulsion system which is more fully described in my patent application Ser. No. 213,573 filed Dec. 29, 1971. The expelled hydrazine passes from the fuel tanks through a fuel metering valve and into a Shell 405 catalyst decomposi tion chamber or reactor.

Inside the reactor, hydrazine (N H decomposes on the catalyst in the reactor to produce an exhaust gas consisting of hydrogen, nitrogen and ammonia. These gases drive a vane type gas motor which through reduction gears drives a shrouded propeller. Exhaust from the motor passes through conduits to a gas operated water pump.

The water pump is employed to pump ambient water into the hydrazine container to either displace a piston or to collapse bellows as described in the above referred to patent application. A manual pump actuator lever is employed to initiate the operation of the water pump. Because the water pump operates from exhaust gases, water must first be pumped by hand into the hydrazine container in order to initiate the action of the hydrazine reactor.

I claim:

I. A portable swimmer propulsion unit comprising:

a hydrazine decomposition reactor;

a positive expulsion hydrazine fuel tank for supplying hydrazine to said reactor;

a gas motor utilizing gas produced by said reactor;

driving means driven by said motor for driving said unit through the water;

a gas driven pump having an exhaust gas outlet to ambient water and operatively connected for pumping water into said tanks at a predetermined rate depending on the volume of exhaust gas passing through said pump from said motor;

a conduit connected to said motor for allowing passage of the exhaust gas from said motor to said pump; and

a manual pump actuator lever in association with said pump for initiating the displacement of said hydrazme;

whereby initial operation of the mannual pump actuator lever supplies an amount of hydrazine to the reactor for generating sufficient gas to drive the motor and the exhaust gas from the motor is used for controlling additional amounts of hydrazine delivered to the reactor. 

1. A portable swimmer propulsion unit comprising: a hydrazine decomposition reactor; a positive expulsion hydrazine fuel tank for supplying hydrazine to said reactor; a gas motor utilizing gas produced by said reactor; driving means driven by said motor for driving said unit through the water; a gas driven pump having an exhaust gas outlet to ambient water and operatively connected for pumping water into said tanks at a predetermined rate depending on the volume of exhaust gas passing through said pump from said motor; a conduit connected to said motor for allowing passage of the exhaust gas from said motor to said pump; and a manual pump actuator lever in association with said pump for initiating the displacement of said hydrazine; whereby initial operation of the mannual pump actuator lever supplies an amount of hydrazine to the reactor for generating sufficient gas to drive the motor and the exhaust gas from the motor is used for controlling additional amounts of hydrazine delivered to the reactor. 